• Nathan Fox

Assumption? Prediction.

Test 25 - Section 4 - Question 18

Logical Reasoning

Difficulty: 2

Sufficient Assumption questions are vastly easier when you predict the answer. Train yourself to predict the answer before you proceed to the answer choices.

Premise: Plants do not have nervous systems.

Premise: Having a nervous system is necessary to experience pain.

Fact, if those two premises are true: Plants do not experience pain.

Bullshit conclusion: Plants cannot be mistreated.

Wait, what? Where did "mistreated" come from? It wasn't mentioned anywhere except the conclusion. You're not allowed to bring up new shit in your conclusion. (That slogan is on the shortlist of LSAT Teacher tattoos that I should get.)

Sufficient Assumption questions ask us to make the argument WIN. In order to win an argument, we have to link the premises to the conclusion in a way that is rock solid. 

Here, my prediction jumps to mind instantly: "If you can't feel pain, you can't be mistreated."

A) No, this answer confuses sufficient and necessary. We know that plants can't experience pain. We need "if you can't feel pain you can't be mistreated." This one is about things that can feel pain. If you're tempted by this answer, you need to get better at sufficient and necessary.

B) We already know that plants that don't have nervous statements can't feel pain. This answer restates a premise and fails to bridge the gap to "can't be mistreated." 

C) We already know plants don't have nervous systems and can't feel pain. This does nothing.

D) Yep. This matches my prediction exactly. If this is true, then it proves the conclusion of the argument to be correct when combined with the premises.

E) This confuses sufficient for necessary. Plants don't have nervous systems, so this doesn't apply to plants.

The correct answer is D and it's entirely predictable once you know what you're supposed to be doing on Sufficient Assumption questions. Keep practicing!

Get more of these explanations from the LSAT Demon


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